Method of recovering bromine and iodine conjointly



METHOD OF RECOVERING BROMINE AND IODINE 'CONJOINTLY Filed Nov. 23, 1931Raw Brim.

I (pm/ g gzlzzii 4 V Suspension A Br V 7 Filter Cake A 5 +4 filtrate 7 H50 3Q ifgjggif @cipitator H 5 Distillate z I HI) HBP 51,252 gs on I 5(xv (fizz @ltzr} Filtrata mt Cake H51 925 Ra a H 50 I2 I HBr 50in. A 50Fig.1

INVENTOR BY @MJZG/L Jfivmaa AT ORNEY which is readily soluble in water.Accordingly, Fe 7 I Patented Sept. 19, 1933 I a 7 r UNITED ESTENT,OFFICE.)

METHOD, OF RECOVERING BRoMINE AND IODINE CONJOINTLY;

Coulter W. Jones, Shreveport, La., assig'nor to f Jones ChemicalCompany, Inc., McDade, La., a'corporation of Louisiana ApplicationNovember 23, 1931 Serial N0. 576,768

- 13 Claims. (01. 2s+217l This invention relatesto methods for recover-.salts has not been'considered feasible owing to ing bromine and iodinefrom mineral waters and the appreciable solubility of ;silverbromide as7 mother liquors in which normally such halogens compared with theiodide, particularly in brines Y are present in combined form inexceedingly of fairly high salt content. While silver bromide 5 smallamount. l 7 l is a relatively insoluble compound, it is sufiici'ent- Ina prior application, Serial No. 321,367, filed 1y soluble that thepercentage loss of silver com- November 23,1928, now Patent 1,837,777 Ihave pound in v recovering bromine in thisway fromvv described a methodof recovering iodine from usual sources; such as mineral watersionmothermineral waters and the like wherein the same liquors, is too great to,permit profitablecopera 10 is precipitated in the form of the. insolublesilver tion at normal prices for silver. I have found, iodide'which isseparated fromthe aqueous mehowever, that losses-ofusilver dissolved inthe dium and worked up for the production of iodine waste liquor fromthe precipitation of 'the -comor commercial iodine compounds, Theaforebined silver halides may be reduced toa prac said method is capableof recovering iodine tically negligible amount bytreating the liquor 15when present in as small amount as 5 parts with a reagent capable ofproducing a more in-;: per million, and without appreciable silverlosses soluble compound than silver bromide, separat inv the wasteliquors. j ing the 'precipitateso formed and recovering the Thenaturally occurring iodiferous brines are silver-therefro m.- Assuitable reagents I may likewise known to contain bromine, as well, anduse a-metallic iodide, or sulphide more soluble, 20 usually inamountconsiderably'exceeding that in water than silvergi'odide or sulphide.The

of the iodine. The usual method of extracting invention, then, consistsin the steps hereinafter bromine from such brines consists inchlorinatfully described and particularly pointed outin ing or otherwiseoxidizing the brine to liberate the claims, the annexed drawing andfollowing the bromine in the elemental state, whereupon descriptionsetting-forth but a few of the var-i- 25 the bromine is removed as vaporbysteaming. ous ways inwhichthe principle of the invention or blowingout with air and the vaporsarere may-be used. a, 1 covered in knownmanner by absorption in a In said 'drawin'gwsuitable medium, such as analkali or active The single figure is a flow sheet showing the.charcoal. Q A somewhat similar procedure has sequence of, steps andmovement of materials; been developed for the recovery of iodine alone,inrone preferred embodimentof the invention;- f as more particularlydescribed in a patent ap- My improved method willbe describedillusplicationof myself and J. J. Grebe, Serial No. tratively,;.asapplied to the recovery oi bromine 388,622, filed August 26, 1929 nowPatent 1,; and iodine conjointly from aynatural brine hav-' 853,621.However, it is not practicable-to reing approximately the; compositionas shown 35 cover both iodine and bromine togetherin-a by thefollowingan'alysiswv 7 process wherein thebromine is liberated in theelemental state by oxidation, since the liber aspelfic mw yf" T" T *fL036 NaCl" 4. 87 percent tion of the bromine 1s accompanied by theox1da, I g t'on f the iodine to'the non-volatile iodate Mgch per r CaClz0. 26 percent mineral waters and the like from which bromine B I r r T01 p r2 0.02 per cent has been extracted by vaporizat on cannot be I2 O004 p worked simultaneously for-the recovery of iodine figfi j gg'."ff"i7'7" 012 N I a by vaporizing as free iodine, nor subsequently 'f v"" 'fon a profitable commercial scale for recovery of ,The method,however,may beappliedjgen'eral iodine by precipitation with a silversalt because ly for the treatment of ,natural brines and of theconsiderably greater solubility, of silver mother liquors containingboth bromine and iodate as compared with the iodide With the iodine inwidely varying proportions and extremely small amounts of iodineactually presamounts, and the specific example herein de 50 ent in suchcases no satisfactory method of, rescribed in detail is not toberegarded as a lim- 1105 ducing the highly stable iodate to free iodineitation upon the invention.

or to iodide is available which is capable of Referring to the drawingas illustratingthe giving a good recovery at a suitable cost.consecutive steps -comprising one embodiment The direct precipitationvof both bromine and of my improvedmethod, the raw; brine is in-, 55iodine together fron jthe brine as the silver troduced into asuitableapparatuswhereinit 0 is mixed, preferably with agitation, with asolution or suspension of a'relatively soluble silver salt, e.g. silversulphate or nitrate. Silver chloride, which is less insoluble than thebromide, may alsofbe used, although with the latter more agitation: anda longer reaction timevvill be required than in the case of a moresoluble reagent. .A precipitate of silver bromide and silver iodide isformed, the soluble silver salt be? perience.

residue containing silver sulphate.

ing added preferably in amount to avoid any substantial excess thereof..The.preoipitated sile ver halides are then filtered through anyconvenient type of filter, for whicheperationit may. I

sulphide, for instance by: introducing hydrogen sulphide gas inslight-excess. A precipitate of silver sulphide is-thereby formed,which. isv fil teredfrom the aqueous solution, The latterzislsubstantially free from silver compounds in de tectable amount and mayberuntoWaste. -The= precipitate or" silver sulphide'm'ay be' converted:to 'a'soluble silver salt by treatment with. a

strong mineral acid, eg. sulphuricacidor nitric acid, and the silversalt solution may bereturned to the first step for treating: the raw Theprecipitate ofsilver bromid'eandsilven iodide is treated with areagentcapableofde composing the silver compounds, so as to sepa-ratetheha'logens and to reconstitute a silver salt suitable for useintreating a further quantity offraw brine. 'Thismay be donebychlorinating,"0r more advantageously by distilling With sulphuric acid?in which latter" case the halogens are distilled off as hydrogen halidetogether with more or less freev iodine, leaving a- Sucl'i residue, maybe combined with the-silver compound recovered from the originalfiltrate and re-; turned to the first s tep;:v The distillateconsistingfof a mixture of iodine, hydriodic acid and hydrobrom'ic acid"may be absorbedin water. In-

order to efiecta'separation of the two halogens inth-isdistillatedtmaybe--oXidized-tocon- "ivert the hydriodicacid-present to'frce iodine;

and thenfiltered to separate the totaliodine: from the aqueoushydi'obromic acid solution. As

a-;,,s,uitable; oxidizing agent bromine or ferric- ,bromide may beemployed. The iodine so recovered ,may be purified in the usual wayto;

makeia;marketableproduct, hile the hydro bromic acid solution .may beWorked up by known methods for the preparation of commer-, cial"bromides or free bromine.

Working in thisway With a-raW brine having the analysis given above, I"am able to'recover- QOTper cent or more of the iodine and bromine,

originally present therein; and, moreover; to-

, reduce silver losses to apractically negligible figure. The method isfurther advantageous in that it requires no acidification of the rawbrine. Instead; oi treating the original filtrate with hydrogen sulphideor a soluble sulphide, asdescribed, I may use a soluble iodide, e.g. analkali; metaliodide; which is to be added in amount correspondingclosely to the silver content of the filtrate. Such iodide may besupplied as a solution thereof or a sumcient amount of raw brine tofurnishthe requisite iodide may be used, The precipitate of silveriodide formed ,may be filtered off and furtherprocessed, to recoveriodine and silver separately, or more conveniently may be added to themain precipitate of. silver bromide and silver iodide to be Worked upfor the separation of the two halogens and silver in accordancewith theprocedure as al ready set forth.

the aqueous solution or liquor maybe effected by any suitable procedure.Instead of filtration, sedimentation and decantation cor centrifugalseparation; may be utilized; Heating and subsequent cooling of thesuspension may be resorted to, it desired, to coagulate-the precipitateprior to its separation from the solution," in which case. heat exchangemay be employed to con--- serve the-heatlof the solution andreduceheatrequirement for the operation.

Incertainof the claims the term sol'uble sulphide is understood toinclude hydrogen sulphide aswell as-Watersoluble m etallicsulphidesOther modes: of applying theprinciple ofmy invention maybeemployedinsteadofthe oneexplained, changebeing made as regards the vThe, separationxof the precipitate of silver bromide and. iodide in thefirst instance, or of. silver sulphide or iodide in the later step,from,

method herein disclosed, provided-thestep or steps stated by any ofthefollowing" claims or the equivalent of such statedstep orsteps beemployed. I i

I therefore particularly" point out Whichcomprises adding; theretoasilver 'salt more solublein water than silver bromide preferablyinamount chemically equivalent to such-- bromide and iodide, separatingthe resulting precipitate of silver bromideand silver iodide fromtheaqucousgsolution, treating the precipitate toseparate-thehalogens fromthe silver therein and recovering residual silver from said aqueoussolution by precipitationas anyinsoluble silvercompound. I r

2: They method silversalt more soluble in'waterthan silver bromidepreferably -inamount chemically eduiva lent to suchbromide a'hd.iodide-, separating the;

resulting precipitate of silver bromide andsilveriodidefrom' the-=aqueous solution, --treating the latter with: a: reagent from' theclass consisting-- of soluble iodides and" sulphides to precipitateresidual silver therein as an insoluble silver com'--' pound andseparating the precipitat'eif 3. The method of :recovering bromine andiodine conjointly; from mineral waters and the like containing thesamefas bromide and iodide; respectively,v which comprisesaddingithereto asilver salt more soluble in Waterthan silver bromidepreferably'in amount chemically'equivaand distinctly claim as myinvention:- r

1 The method of recovering bromine and iodine conjointl-yfrom mineralwatersand the likecontaining the same in relatively small amount'asbromide and iodide, respectively,

I of recovering bromine and;

iodineconjointly from. mineral *Waters andthe like containing the sameasbromide-and iodide; V respectively, 'whichcomprises adding theretoa lentto such bromide andiodid'e; s'eparating they resulting precipitate ofsilver'bromideand silver iodide from the aqueous solution, treating-theprecipitate to liberate" the halogenstherefrom andto recoverthe's'ilvenimcombinedform= re actable in said first step, treating saidaqueous solution with a soluble sulphide to precipitate residual silvertherein as sulphide and separating the precipitate.

4. The method of recovering bromine and iodine conjointly from mineralWaters and the like containing the same asvbromide and iodide,respectively, which comprises adding thereto a silver salt more solublein water than silver bromide preferably in amount chemically equivalentto such bromide and iodide, separating the resulting precipitate ofsilver bromide and silver iodide from the aqueous solution, reactingsaid precipitate with sulphuric acid to convert the halogen constituentsthereof to'free halogen or silver salt more soluble in water than silverbromide preferably in amount chemically equiv alent to such bromide andiodide, separating the resulting precipitate of silver bromide andsilver iodide from the aqueous solution, reacting said precipitate withsulphuric acid to convert the halogen constituent thereof to freehalogen or hydrogen halide and the silver constituent to silversulphate, separating the latter from the halogen compounds, oxidizingsuch compounds to convert the iodine component thereof to free iodinewhile the bromine component remains as hydrogen bromide, separating theiodine from the hydrogen bromide; treating said aqueous solution withhydrogen sulphide to precipitate residual silver therein as sulphide,separating the precipitate and converting the same to a silver compoundreactable in said first step.

6. The method of recovering bromine an iodine conjointly from mineralwaters and the like containing the same as bromide and iodide,respectively, which comprises adding silver sulphate thereto, in amountsubstantially chemically equivalent to such bromide and iodide,separating the resulting precipitate of silver bromide and silver iodidefrom the aqueous solution, reacting said precipitate with sulphuric acidto convert the halogen constituent thereof to free halogen or hydrogenhalide and the silver constituent to silver sulphate, separating thelatter from the halogen compounds, oxidizing such compounds to convertthe iodine compo-' nent thereof to free iodine while the brominecomponent remains as hydrogen bromide, separating the iodine from thehydrogen bromide;.

treating said aqueous solution with hydrogen sulphide to precipitateresidual silver therein as sulphide, separating the precipitate,converting the same to sulphate by reacting with sulphric acid, andreturning the silver sulphate recovered from the aforesaid treatment ofthe original precipitate and filtrate, respectively, to"

the first step.

7. In a method of recovering bromine and iodine conjcintly from mineralwaters and the of silver bromide and silver iodide with sulphuric:iodine from the non-volatile residue of silver like containing the sameas bromide and iodide, wherein said halogens are precipitated as thecorresponding silver halides and separated from the aqueous solution,the step'which consists in treating said solution with a reagent fromthe class consisting of soluble iodides and sulphides to precipitateresidual silver therein as an insoluble silver compound. 8. In a methodof recovering bromine and iodine ,conjointly from mineral waters and thelike containing'the same asbromide and iodide, respectively, the stepswhich consist in precipitating'said halogens together as thecorrespond-- ing silver halides, distillingv the precipitate withsulphuric acid, whereby the halogens are obtained in the distillateleaving a residue of silver sulphate.- a v v 9. In. a method ofrecovering bromine "and. iodine conjointly from mineral waters and thelike containing the same as bromide and iodide, respectively, the stepswhich consist in precipi-'- tating said halogens together as thecorresponding silver halides, distilling the precipitate with sulphuricacid, whereby the halogens are obtained in the distillate leaving aresidue of 00 silver sulphate, oxidizing such distillate sufiiciently'toconvert the iodine constituent thereof to free iodine and separatingsuch free iodine from the accompanying hydrogenbromide. f

10. In a method of recovering bromine and iodine conjointly from mineralwaters and the like, wherein said. halogens are precipitated together asthe corresponding silver'halides, the step which consists in treatingsuch precipitate of silver bromide and silver iodide with a chemicalreagent capable of decomposing thesame to form free halogen or volatilehalogen, compounds and leave a non-volatile silver compound;

iodine conjointly from mineral waters and the like, wherein saidhalogens are precipitated together as'the corresponding silver halides,the stepswhich-consist in reacting such precipitate acid and distillingoil the halogens as a mixture of hydrogen bromide, hydrogen, iodide andfree sulphate. Y a

12. In a method of recovering bromine and iodine conjointly from mineralwaters and 'thelike, wherein said halogens are precipitated together asthe corresponding silver halides, the steps which consist in reactingsuch precipitate of silver bromide and silver iodide with sulphuricacid, distilling off the halogens as a mix-,

ture of hydrogen bromide, hydrogen iodideand.

free iodine, from the non-volatile residue of sil ver sulphate,oxidizing the hydrogen iodide component of the distillateto free iodine,and separating the free iodine from the hydrogen bromide, r 13. In amethod of extracting bromine and iodine conjointly from aqueoussolutions containing the same as bromide and iodide, respec- 14o tively,the steps which consist in converting said bromide and iodide to thecorresponding insoluble silver salts, separating ,the'latter from thesolution and recovering residual silverfrom said solution byprecipitating as an insoluble silver sulphide.

COUL'IER w. JONES.

